JP3554293B2 - Strobe device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a strobe device, for example, to a strobe device suitable for being built in or externally attached to various cameras.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a so-called strobe device that instantaneously illuminates a subject at the time of shooting has been widely used as a camera for shooting a silver halide photograph or a digital camera for shooting an image using an image sensor.
[0003]
The above-described conventional strobe device generally includes a charging circuit that boosts a power supply voltage and charges a capacitor with energy for light emission of a discharge tube, and a trigger circuit that promotes (starts) light emission. In the prior application, Japanese Patent Application No. 2000-31384 (which was not disclosed at the time of filing of the present application), a piezoelectric transformer that is lighter, saves space, and has more flexibility in element shape than a wire-wound transformer is disclosed. And a strobe device adopted for the trigger circuit.
[0004]
[Problems to be solved by the invention]
According to the strobe device having the piezoelectric transformer as described above, it is not necessary to employ a winding transformer having a large outer shape and a heavy weight, so that the entire shape can be reduced in size and weight, and the strobe device suitable for being carried by a user. Is realized.
[0005]
However, since a strobe device including a piezoelectric transformer does not include a winding transformer, an operation sound during charging, which is generally used in a conventional strobe device including a winding transformer, that is, a charged state (amount of charge) of a capacitor. There is no operation noise caused by a change in the resonance state of the winding coil constituting the winding transformer according to the above.
[0006]
For this reason, a strobe device having a piezoelectric transformer is expected to make it difficult for a user who is familiar with a conventional strobe device having a winding transformer to understand the operation state and give a sense of incongruity.
[0007]
Accordingly, an object of the present invention is to notify a user of at least an operation state in a strobe device including a piezoelectric transformer.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a strobe device according to the present invention has the following configuration.
[0009]
That is, a discharge tube for flash, a capacitor for storing electric energy for causing the discharge tube to emit light, a charging circuit including a piezoelectric transformer as boosting means for charging the capacitor with electric energy, and a predetermined circuit for promoting discharge of the discharge tube A trigger circuit for generating a high-voltage signal of
A sounding plate that resonates at an audible frequency lower than a driving frequency of the piezoelectric transformer in response to a physical (mechanical) vibration generated when the piezoelectric transformer is driven, to notify a user of an operation state of the strobe device; The piezoelectric transformer is provided in contact with the piezoelectric transformer.
[0010]
Thus, in the strobe device including the piezoelectric transformer, at least the operation state can be notified to the user, and the convenience is improved.
[0011]
In a preferred embodiment, the charging circuit includes a charging voltage detection circuit that detects a charging state of the capacitor, and a burst oscillation circuit that burst-oscillates an oscillation signal serving as a basis of the driving frequency according to the charging state of the capacitor. And
The charging circuit adjusts the driving frequency in accordance with a ratio between an oscillation period and a stop period of the oscillation signal, which is changed by the burst oscillation circuit in accordance with a state of charge of the capacitor, thereby controlling the sounding plate. Depending on the change in the resonance state of the sounding plate caused by the change in the drive state of the piezoelectric transformer, at least the state of the capacitor being charged and the sounding state that is different between the fully charged state and the resonance state of the piezoelectric transformer. It is good to change to
[0012]
Thus, in the strobe device including the piezoelectric transformer, the state of charge of the capacitor by the charging circuit can be notified to the user by a change in the sounding state of the sounding plate, and the convenience is further improved.
[0013]
Alternatively, in another preferred embodiment, the charging circuit includes a charging voltage detection circuit that detects a state of charge of the capacitor, and an oscillation frequency of an oscillation signal that is a basis of the driving frequency according to the state of charge of the capacitor. And an oscillation circuit for changing
The charging circuit adjusts the driving frequency in accordance with an oscillation frequency changed by the oscillation circuit in accordance with a charging state of the capacitor, so that a resonance sound generated from the sounding plate is changed in a driving state of the piezoelectric transformer. According to the change in the resonance state of the sounding plate that accompanies the change, it is preferable that the tone is changed at least between a state in which the capacitor is being charged and a state in which the capacitor is fully charged.
[0014]
Thus, in the strobe device including the piezoelectric transformer, the state of charge of the capacitor by the charging circuit can be notified to the user by a change in the tone of the sounding plate, and the convenience is further improved.
[0015]
Any of the above strobe devices is suitable for use in a camera built in or external to the camera, in which case the trigger circuit only needs to operate in response to a shutter operation of the camera.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which a strobe device according to the present invention is built in or externally attached to various cameras and applied to a suitable strobe device will be described in detail with reference to the drawings.
[0017]
[First Embodiment]
FIG. 1 is a block diagram illustrating a circuit configuration of the strobe device according to the first embodiment.
[0018]
The strobe device shown in FIG. 1 is roughly divided into a discharge tube (for example, a xenon discharge tube) 4 for flash, a discharge capacitor 3 for storing electric energy for causing the discharge tube 4 to emit light, and a charging circuit 1 for charging the discharge capacitor 3 with electric energy. And a trigger circuit 2 for generating a high voltage signal for urging the discharge tube 4 to discharge.
[0019]
In the charging circuit 1, the drive circuit 12 drives the piezoelectric transformer 13 according to an oscillation signal output from the oscillation circuit 11. The output voltage of the piezoelectric transformer 13 is rectified by a rectifying circuit including rectifying diodes 15 and 16 and then charged into the discharge capacitor 3 as electric energy for causing the discharge tube 4 to emit light. In the present embodiment, the sounding plate 5 is provided on the piezoelectric transformer 13 (details will be described later).
[0020]
Incidentally, as for the individual circuit configurations of the oscillation circuit 11 and the drive circuit 12, a general device may be employed at present, and therefore detailed description in the present embodiment will be omitted.
[0021]
The trigger circuit 2 is connected to a trigger terminal of the discharge tube 4, and the discharge tube 4 flashes with energy charged in the discharge capacitor 3 using a high voltage output from the trigger circuit 2 at a predetermined timing as a trigger signal. Emits.
[0022]
In this embodiment, a winding transformer may be used as the boosting means for obtaining a high voltage for the trigger signal in the trigger circuit 2. However, in order to reduce the size and weight of the entire flash device, It is preferable to employ a piezoelectric transformer element (the same applies to the following embodiments).
[0023]
FIG. 2 is a perspective view showing a structure around a piezoelectric transformer of the strobe device according to the first embodiment.
[0024]
As shown in the figure, the piezoelectric transformer 13 is a so-called single-plate type or a laminated type including a plurality of internal electrodes inside a general Rosen-type piezoelectric transformer element (the same applies to the following embodiments). ), Which functions as boosting means for obtaining a high voltage for charging the discharge capacitor 3 with electric energy. In the present embodiment, one end of the sounding plate 5 is provided on the end face of the primary side region in the longitudinal direction of the piezoelectric transformer 13 in a state in which it is in contact with the other end of the sounding plate 5. It is fixed to a printed circuit board (PCB) or a case with an adhesive or the like.
[0025]
In the present embodiment, the sounding plate 5 is, for example, a metal member made of an elastic material, and has a size and a shape that physically (mechanically) vibrate at a driving frequency in a non-audible region of about 100 kHz. Is designed to resonate at a natural frequency in the audible region lower than the drive frequency (for example, a resonance frequency which is about a fraction of the drive frequency) in accordance with the vibration of the drive frequency.
[0026]
In a preferred embodiment, when the strobe device shown in FIG. 1 is a strobe device for a camera built in or external to various cameras, the trigger circuit 2 may be operated in response to a shutter operation of the camera.
[0027]
According to the strobe device of the present embodiment having such a device configuration, during operation of the strobe device, the sounding plate 5 uses the vibration of the piezoelectric transformer 13 driven in the non-audible frequency range to generate the audio frequency. , The user can recognize the operation state of the flash device, and the convenience is improved.
[0028]
In the present embodiment described above, a general Rosen-type piezoelectric transformer element as shown in FIG. 2 is employed as the piezoelectric transformer 13, but the piezoelectric transformer element to be employed in the charging circuit 1 is limited to this type. Instead, another type of piezoelectric transformer element may be employed. In this case, the abutting position of the sounding plate 5 may be a position where physical vibration is greatest when the employed piezoelectric transformer element is driven.
[0029]
[Second embodiment]
Next, a second embodiment based on the strobe device according to the first embodiment will be described. In the following description, the same configuration as that of the first embodiment will not be described repeatedly, and will be described focusing on the characteristic portions of the present embodiment.
[0030]
In the first embodiment described above, the sounding plate 5 sounds regardless of the state of charge of the discharge capacitor 3. Therefore, in the present embodiment, an object of the present invention is to notify the user of the state of charge of the discharge capacitor 3 by the charging circuit so as to be recognizable by a change in the sounding state of the sounding plate 5.
[0031]
FIG. 3 is a block diagram showing a circuit configuration of the strobe device according to the second embodiment. The strobe device shown in FIG. 3 is different from the oscillation circuit 11 provided in the charging circuit 1 in the charging circuit 1A. The flash device according to the first embodiment differs from the flash device of the first embodiment (FIG. 1) in that the flash device further includes a burst oscillation circuit 18 and further includes a charging voltage detection circuit 17 that controls the oscillation state of the burst oscillation circuit 18.
[0032]
FIG. 4 is a diagram illustrating a circuit configuration of the charging voltage detection circuit 17 included in the charging circuit 1A of the strobe device according to the second embodiment.
[0033]
As shown in the figure, the charging voltage detecting circuit 17 includes voltage dividing resistors 17a and 17b for detecting the charging voltage of the discharge capacitor 3, and an error amplifier for outputting the result of comparing the detected charging voltage with a predetermined reference voltage Vref. Alternatively, it has a comparator 17c. The output signal of the error amplifier or comparator 17c is input to a control terminal (not shown) of the burst oscillation circuit 18.
[0034]
The burst oscillation circuit 18 is an oscillation circuit that performs general burst control at present, and appropriately turns on a resonance frequency f1 of about 100 kHz for driving the piezoelectric transformer 13 at a frequency f2 of about several hundred Hz lower than the frequency. An intermittent (burst) oscillation signal obtained by turning off is output to the drive circuit 12.
[0035]
That is, in the present embodiment, the burst oscillation circuit 18 continuously outputs only the resonance frequency f1 while the discharge capacitor 3 is being charged, for example, by turning off the frequency f2. The piezoelectric transformer 13 is driven by the drive circuit 12 in accordance with the resonance frequency f1 continuously output from the burst oscillation circuit 18. At this time, the sounding plate 5 has a resonance frequency in which a tone having a predetermined audible frequency is continuous. Produce the sound.
[0036]
Next, as described above, charging of the discharge capacitor 3 proceeds, and when the discharge capacitor 3 is fully charged, the charge voltage detection circuit 17 sets the full charge state to a predetermined charge voltage by the voltage dividing resistors 17a and 17b. As a result, the error amplifier or comparator 17c inputs a predetermined output signal to the burst oscillation circuit 18. At this time, the burst oscillation circuit 18 outputs a predetermined intermittent oscillation signal to the drive circuit 12 by starting an operation of appropriately turning on and off the frequency f2 with respect to the resonance frequency f1. The piezoelectric transformer 13 starts intermittent driving by the drive circuit 12 in response to the intermittent oscillation signal output from the burst oscillation circuit 18. Changes, the sounding plate 5 emits a resonance sound in which the timbre of the predetermined audible frequency is intermittent.
[0037]
According to the strobe device of the present embodiment having such a device configuration, while the discharge capacitor 3 is being charged, the sounding plate 5 continuously emits an audio frequency at an audible frequency, and when fully charged, the sounding plate 5 is audible. Since the sound is generated intermittently at the frequency, the user can recognize the state of charge of the discharge capacitor 3 by the charging circuit 1A by a change in the sounding state of the sounding plate 5, and the convenience is further improved.
[0038]
In the above-described second embodiment, for simplicity of description, the mode of the oscillation signal output from the burst oscillation circuit 18 is defined as a charged state in which the resonance frequency f1 is continuous and a fully charged state in which the intermittent oscillation signal is generated. However, the present invention is not limited to this control procedure. By appropriately turning on / off the frequency f2 with respect to the resonance frequency f1, the oscillation period and the stop period of the oscillation signal output from the burst oscillation circuit 18 are changed. May be controlled so as to be adjusted to different rates between the charged state and the fully charged state.
[0039]
In the above-described second embodiment, two types of oscillation states are realized by the burst oscillation circuit 18. However, instead of the burst oscillation circuit 18, a voltage that outputs a signal having an oscillation frequency corresponding to the input control voltage is output. A control oscillation circuit (VCO) may be employed. However, in this case, according to the control voltage set by the charging voltage detection circuit 17, the oscillation signal set from the voltage controlled oscillation circuit to the drive circuit 12 is not an intermittent oscillation signal in any of the charging states, but is different. Since the oscillation signal is an oscillation signal of the oscillation frequency, a change in the sounding state of the sounding plate 5 is realized as a change in timbre.
[0040]
Further, in the second embodiment described above, the change in the sounding state of the sounding plate 5 is realized in two states, that is, the state in which the discharge capacitor 3 is being charged and the state in which the discharge capacitor 3 is fully charged. By configuring the internal voltage comparison function to be able to detect a plurality of levels of voltages, the mode of the oscillation signal output from the burst oscillation circuit 18 can be three or more, and accordingly, three or more sounding states can be sounded. It may be realized by the plate 5.
[0041]
【The invention's effect】
According to the present invention described above, in a strobe device including a piezoelectric transformer, at least an operation state can be notified to a user, and user convenience can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a circuit configuration of a strobe device according to a first embodiment.
FIG. 2 is a perspective view illustrating a structure around a piezoelectric transformer of the strobe device according to the first embodiment.
FIG. 3 is a block diagram illustrating a circuit configuration of a strobe device according to a second embodiment.
FIG. 4 is a diagram exemplifying a circuit configuration of a charging voltage detection circuit 17 included in a charging circuit 1A of a strobe device according to a second embodiment.
[Explanation of symbols]
1, 1A: charging circuit,
2: trigger circuit,
3: Discharge capacitor,
4: Discharge tube,
5: sounding board,
11: oscillation circuit,
12: drive circuit,
13: Piezoelectric transformer,
15, 16: rectifier diode,
17: charging voltage detection circuit,
17a, 17b: voltage dividing resistance,
17c: error amplifier or comparator,
18: Burst oscillation circuit,

Claims (4)

A discharge tube for flash, a capacitor for storing electric energy for causing the discharge tube to emit light, a charging circuit including a piezoelectric transformer as a boosting means for charging the capacitor with electric energy, and a predetermined voltage for promoting discharge of the discharge tube. A trigger circuit for generating a voltage signal,
In order to notify the user of the operation state of the strobe device, a sounding plate that resonates at an audible frequency lower than the drive frequency of the piezoelectric transformer in accordance with physical vibration generated at the time of driving the piezoelectric transformer is provided on the piezoelectric transformer. A strobe device characterized by being provided in abutting state. The charging circuit includes:
A charging voltage detection circuit that detects a state of charge of the capacitor;
A burst oscillation circuit that burst-oscillates an oscillation signal based on the drive frequency in accordance with a state of charge of the capacitor;
The charging circuit includes:
By adjusting the drive frequency according to the ratio between the oscillation period and the stop period of the oscillation signal, which is changed by the burst oscillation circuit according to the state of charge of the capacitor, the resonance sound generated from the sounding plate Changing at least a state in which the capacitor is being charged, and a state in which the capacitor is fully charged, in accordance with a change in the resonance state of the sounding plate caused by a change in the drive state of the piezoelectric transformer. The strobe device according to claim 1, wherein: The charging circuit includes:
A charging voltage detection circuit that detects a state of charge of the capacitor;
An oscillation circuit that changes an oscillation frequency of an oscillation signal that is a basis of the drive frequency according to a state of charge of the capacitor;
The charging circuit includes:
By adjusting the drive frequency according to the oscillation frequency changed by the oscillation circuit according to the state of charge of the capacitor, a resonance sound generated from the sounding plate is generated with a change in the drive state of the piezoelectric transformer. 2. The strobe device according to claim 1, wherein the tone is changed to a different tone at least between a state in which the capacitor is being charged and a fully charged state in accordance with a change in the resonance state of the sounding plate. 4. The strobe device according to claim 1, wherein the strobe device is a strobe device for a camera built in or external to a camera, and the trigger circuit operates in response to a shutter operation of the camera. The strobe device according to any one of the above.

Images